April, 1943
FRACTIONATION OF THE R A R E
hydrocarbons, have been shown to be stabilized by resonance. This stabilization is least in primary radicals, greatest in tertiary radicals and is very probably responsible for the observed difference in rates of removal of primary, secondary and tertiary hydrogen atoms. 2. This approach gives a method for predicting the relative rates of dccomposition of radicals, as well as their relative rates of formation.
[CONTRIBUTION FROM THE
EARTHSBY ZEOLITE ACTION
595
3. Long chain radicals have the ability to isomerize unimolecularly. This factor has been taken into account in calculating the products of decomposition of hexanes, heptanes and octanes. 4. These considerations lead to considerably improved agreement between the calculated and observed products of the decomposition of para& hydrocarbons. WASHINGTON, D . C.
DEPARTMENT OB
RECEIVEDDECEXBER 17, 1942
CHEMISTRY, P U R D W UNIVERSITY]
Fractionation of the Rare Earths by Zeolite Action*t2 BY R. G. RUSSELL’AND D. W. PEARCE The second geochemical principle of V. M. Goldschmidt4 dealt with the fact that individual minerals are seldom “pure chemical compounds” but usually contain greater or smaller amounts of foreign elements. The explanation was made upon the size and valence relationships between the normal ion of the lattice and the foreign, replacing, ion. Thus, for example, the presence of traces of scandium in magnesium silicates crystallizing in the earlier stages of the solidification of the magma was believed due to the similarity in the ionic radii of these cations (Mg+2 0.78, S C +0.83 ~ A.). The greater charge of the Sc+’ ion enhanced its tendency, when in the vicinity of the growing magnesium silicate lattice, to enter into the structure.6 In much the same way the slightly smaller, rather than the slightly larger, cations seem to be preferred by the lattice when a selection must be made from a mixture containing a series of cations of the same valence and of approximately the same size. While these observations of Goldschmidt were concerned with minerals crystallizing from the molten magma, it seemed likely to the present investigators that such replacement of one ion (1) Based upon a thesis submitted by R. G. Russell to the Faculty of Purdue University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy, May, 1942. (2) Presented before the Division of Physical and Inorganic Chemistry at the 104th meeting of the American Chemical Society, Buffalo, N. Y.,September, 1942. (3) Present address, Aluminum Research Laboratories, New Kensington, Pennsylvania. (4) V. M. Goldschmidt, Vidcnskagssclska~els-Skriflcr. I . Mal.nalurv. Klassc Krisfiania, 1923, No. 3; ibid., 1924, No. 4. (5) Valence compensation may be obtained, in such a case, by the more or less simultaneous entrance of another cation of similar size but of valence 1, or by the entrance into the anion of an ion M + ’ rather than Si+‘, or by the formation of a defect lattice with 2 Sc + I as the valence equivalent of 3 M g + * ,or by combinations of such means.
by another might occur in a preferential manner when materials, synthetic or natural, which were capable of ready base-exchange were put into contact with aqueous solutions containing an assortment of ions, such as those of the rare earths, of the same charge but of varying size. Indeed the work of Jenny,6 and of Bray,’ and of many others has dealt with such base-exchange properties of various permutits, clays and soils. Both Jenny and Bray have indicated that “valence and ion size seem to be concerned in this phenomenon.”8 However, Jenny found that the order of preference of his permutit materials for the alkali metal ions was L i t < Na+ < K + < Rb+ < Cs+ which is just the reverse of the order expected from the (crystal) ionic sizes if the assumption is made that a smaller ion of the series is preferred to a larger. He was therefore led to assume, as Wiegner had done before,g that the radii of the hydrated ions, the “hydrodynamic radii,” were ranged in the opposite order due to the increased polarizing effect of the smaller ions upon the water molecules. The result of the latter effect, then, was assumed to be a larger water-envelope and larger over-all size for the hydrated L i t than for the hydrated Cs+ ion. However, the recent work of Fajans’O has shown that the order of apparent molar volume, a t infinite dilution, of the alkali metal ions a t 25’ is probably Na+ < Lit. < K + < Rb+ < Cs+. If this order held during the experiment of Jenny, then the exchange-material had preferentially ( 6 ) Hans Jenny, J . Phys. Chcm., 86, 2217-2258 (1932). (7) R. H. Bray, THIS JOURNAL, 64, 954-963 (1942). (8) Bray, loc. til., p. 956. (9) G. Wiegner, Kolloid-Z., 16, 341-369 (1925). JOURNAL, 64, 868-1378 (1942). (10) K. Fajans, THIS
5%
K . I:.RUSSELL. \ N D D. W. PEARCE
removed from solution the largest species with a reversal, as yet unexplained, bet ween Na + and Lit. In the present work the principal purpose was to study, in a preliminary way, the use of baseexchange materials of high capacity in rare earth separations and to arrive a t working hypotheses with regard to the mechanism of base-exchange as it concerns the ions of these elements. Qualitative Behavior of Zeolites
VOl. 65
Separations of the Rare Earths In the preceding the behavior of certain zeolitic materials toward rare earth solutions was briefly described. In these the ratio by weight of exchange-medium to removable ions was such that the latter were completely removed since they possessed, apparently, the necessary physical and chemical characteristics for entry into the “zeolite lattice” and since they were present to an extent less than the capacity of the exchangematerial. In the following are to be described the results obtained when the exchange-material was in all cases “overloaded,” that is, subjected to contact with a greater amount of exchangeable ions of mixed type than could be accommodated by the weight of exchange-material used.
The fact that ions of many types, including those of the rare earths, were removed from solution by “zeolites” was proved by causing dilute solutions to flow through short towers of various base-exchange materials in the form of the acid or of the sodium salt; the a t r a t e s ( d u e n t s ) were then tested for the ions concerned by the addition of the appropriate reagents. In all cases the total amount of Single-stage Fractionation ion in the original solution was less than that required t o Ce-group Material.-From a rare earth fracreach the capacity of the exchange-material. No particular effort was made to allow the optimum contact time and tional crystallizatior series there was taken a this may in part explain the fact that, in certain cases, fraction composed mainly of La and Nd with small complete removal of the ions was not obtained. amounts of Pr and Sm. The rare earths were Such preliminary experiments indicated that the siliprecipitated as oxalate and the average atomic ceous exchange-material Crystallite 120, a synthetic type,” readily and completely removed Mg+2, Y+a and mixed weight determined to be 141.7 (*0.9) by an yttrium-group ions from dilute solutions of the nitrates, oxalate to permanganate, oxalate to oxide proLa+S ion was similarly removed by Eimer and Amend cedure.14 The oxalate was ignited to oxide, the “Permutit, acc. to Prof. Otto Folin” and Ag+ and C U + ~ latter dissolved in nitric acid, the solution evapoions by the zeolite Decalso.lz On the other hand, solutions of the ions Fe+3 or Th+4in contact with the treated- rated just to dryness and the residue taken up in natural zeolite Super Zeo Dur12 gave evidence of partial distilled water. Portions of this solution, conhydrolysis and precipitation and these ions were only par- taining rare earths to the extent of approximately tially removed from the solution; similar behavior was five times the capacity of the exchange-material, obtained with a solution of ZrO+zusing Hizecol3 and with a solution of UOzf2 using Super Verditelteach of these were poured fifteen times through similar weights exchange-materials being of the treated-natural type; of natural (Super Zeo Dur, Grarhohy,’j Super a neutral nitrate solution of Sc+3 behaved in the same Verdite, Hizeco), synthetic (Crystallite #20) and way with Crystallite #20. The ions Th+4,F e f 3 and Mn+ carbonaceous (Zeo Karb) exchange-materials. were completely removed from solution by the carbonace- The average atomic weights of the rare earths in ous exchange-material Zeo Karb12 when the operations the filtrates were determined and compared with were conducted on the Hi-cycle; however, this same those obtained from the regenerates. Insignifimedium removed practically no S n f 2 from a solution of cant differences in the atomic weights were interstannous chloride in excess hydrochloric acid. In the cases of those ions which hydrolyze readily a t preted to mean that little separation had occurred slightly higher pH values, interferences of this side reac- in these cases. tion are to be expected since the PH often increases when A 12-gram sample of Y-Group Material.-1. a neutral solution passes through siliceous zeolite materials. light brown mixed yttrium group oxides of unThis difficulty may be obviated, as the experiments indicate, by the use of exchange-materials operating on the known source was dissolved in nitric acid, the hydrogen cycle. I n the case of the SnC14‘ solution the solution evaporated just to dryness and the residue rather large hydrogen ion concentration which was pres- taken up in one liter of distilled water. The soluent without doubt offered competition for the small contion was poured six times through a 50-g. sample rentration of Sn+*, since the former is, itself, a regenerant of Crystallite #20 contained in a 12-in. length of for this exchange-material. For this reason removal of the metallic ion from the solution may have been pre- 16-mm. diameter Pyrex tubing. The zeolite was vented. regenerated with concentrated sodium chloride (11) The International Filter Co., Chicago, Ill. (12) The Permutit Co., New York, N. Y. : 13) The Zeolite Sales Co.. X e w York, N Y.
(14) Based upon the method of W. Gibbs, .4?n. Chem. J . , 16, 546 5fi6 (1893): to be described in a forthcoming publication. (1,Y ‘The Graver Tank Co East Chicago, Ind.
April, 1943
FRACTIONATION OF THE RAREEARTHS BY
solution, the rare earths recovered from the regenerate and from the filtrate, and the average atomic weight of the rare earths in each sample determined. The results were 106.9 (*O.O) and 117.3 (*O.l), respectively. The oxide from the regenerate was very light brown in color and that from the filtrate much darker. From the colors of the oxides and the average atomic weights it was concluded that an increased concentration of Y t 3 had been obtained in the regenerate due, apparently, to the readier removal of this ion from the solution by the zeolite. 2. Other experiments were carried out using a neutral yttrium group nitrate solution prepared from the rare earths extracted from a sample of gadolinite. The average atomic weight of the rare earths in this mixture was 111.8 (*0,1), a value in good accord with the high yttrium content of this mineral. Crystallite # 20 was again used as the exchange-medium. Five hundred ml. of the solution, containing about 125 g. of the oxide, was stirred with a 500-g. sample of the zeolite for about four hours. During this time a small amount of light brown sludge formed in the mixture. At the conclusion of the run this was suspended in the solution by agitation and the suspension decanted from the heavier zeolite. The sludge was completely removed from the zeolite by agitating with the distilled water used for washing the latter and the sludge was then removed from the solution by filtration. Determination of the Ce in the sludge as compared with that in the original solution showed that approximately 12% of the original Ce had passed into this oxidate-hydrolyzate. The zeolite was then regenerated with sodium chloride solution and the rare earths recovered from the regenerate and reserved. The filtrate from the sludge and the same sample of zeolite were then again stirred together for four hours as before, the filtrate separated from the zeolite, and the rare earths recovered from the zeolite by regeneration. The rare earths thus recovered were reserved. In this way there was built up, after six regenerates had been obtained, a fraction sufficiently large to start a second series which was thereafter itself carried through two fractionations. For the purpose of estimating the composition of the various fractions, determinations of the average atomic weight were made on small samples taken at certain points during the separations and the colors of the oxides were
ZEOLITE
ACTION
597
observed. The oxides from the regenerates were increasingly lighter in color as the atomic weights decreased while the oxides from the corresponding filtrates were darker and contained heavier earths. Thus, in the first series, the medium brown oxides from the first filtrate fraction had an average atomic weight of 110.4 ( 1.4) while the gradual variation from fraction to fraction was such that the reddish brown oxides from the sixth filtrate had an atomic weight of 114.9 (‘0.6); from the corresponding regenerates the oxides were all light brown and the atomic weight decreased from 103.4 ( t 0 . 4 ) to 102.0 (‘1.1). In the second series, formed by the fractionation of the combined regenerates from the first series, the first filtrate yielded light brown oxides with atomic weight 107.1 (‘0.4) while the first and second regenerates yielded pale brownish-white oxides with the atomic weights95.0 ( t 0 . 1 ) and 96.2 (*O.l), respectively. The preceding data may be interpreted if several facts are recalled. The ionic radii of the rare earths decrease16from La+3(1.22A.) to Lufj (0.99 A,) with the associated Y +3 having a radius (1.06 A.) intermediate between Dyf3 (1.07 k . ) and H o + (1.05 ~ A.). The atomic weights, on the other hand, increase from 138.92 for La to 174.99 for Lu but Y is much lighter, 88.92. Furthermore, with regard to the color of oxide mixtures, the higher oxide of Pr is black and, while this element is of low abundance, the content of its oxide largely determines the color of ceriumgroup mixtures. In the case of yttrium group oxide mixtures the color is similarly determined by the content of the very rare Tb, the higher oxide of which is very dark, and by the content of the principal diluent, the white oxide of the relatively very abundant Y. From the data obtained it is concluded, then, that yttrium, and possibly even the rare earths with atomic weight greater and (crystal) ionic radii less than that of Y+3,was particularly concentrated in the later regenerates of the second series while the elements heavier than yttrium, and of larger radii, were progressively concentrated in the laterjiltrates of the first series. Multiple-stage Fractionation The preceding experiments indicated that a zeolite expresses a preference for certain rare earth ions when a solution containing an assortf
(16) V. M. Goldschmidt, “Kristallchemie,” Handworterbuch der Naturwissenschaften, 2nd ed., G. Fischer, Jena, 1934.
598
R. G. RUSSELLAND D. W. PEARCE
ment of these is subjected to its action provided that the content of the solution exceeds the capacity of the exchange-material. However, the extent of the individual separations plainly showed the necessity of multiple-stage rather than singlestage operations if reasonable efficiency was to be obtained and minimum labor expended. A 50-ft. column of 10-mm. Pyrex glass was therefore set up and filled with Crystallite # 20 which had been regenerated with sodium chloride solution and thoroughly washed with distilled water. At the top of the column about 500 ml. of the rare earth solution, of the same composition and concentration as used in the preceding experiment, was added to a reservoir and was permitted to drip slowly into the zeolite column. The effluent a t the base was tested continuously for rare earths. Approximately 250 ml. of filtrate was collected before the presence of rare earths was detected; a t this point the addition of solution a t the top was discontinued and fractions of 8-ml. volume were taken from the base while the column was allowed to drain. The rare earths were recovered from the individual filtrate fractions by precipitating the oxalates and igniting them to oxides. Fractions 1-14 each contained only a few tenths of a gram of oxide which was insufficient for convenient study of the absorption spectra or for the determination of the atomic weight. From the oxides of the remaining fractions, however, solutions were prepared to contain 1 g. of the oxide as nitrate in 10 ml. of 1 N nitric acid. The absorption spectra of constant thicknesses of these solutions were examined by the use of a hand spectroscope and were compared with the absorption spectra of standard solutions. The results of these analyses are shown in Table IA. Furthermore, the arc spectra of most of the fractions were photographed, mainly in the region X 3900-4900 A., using the Baird Associates grating spectrograph. After the column had drained, the zeolite was washed with 250 ml. of water, the first and last 50-ml. portions being collected separately; both of these showed faintly the strongest Nd band in the absorption spectrum. From these extreme portions of washings the rare earths were recovered as oxalates and ignited to oxides; the latter were light brown in color. The average atomic weights were 109.2 ( k 0 . l ) and 108.0 (f0.4), respectively.
Vol. 65
Following this partial washing, the zeolite was regenerated with 10% sodium chloride solution which was held in a container at the top and allowed to drain slowly through the column. The first portion of the solution issuing from the column contained small amounts of rare earth ions; there was approximately 50 ml. of this. The next portion contained no rare earth ions and very little chloride; there was approximately 200 ml. of this solution. The third portion contained rare earths and sodium chloride. Fractions of this last solution, each of 8-ml. volume, were taken off continuously during the regeneration and until only very small amounts of rare earths were being displaced. The composition of these small fractions was studied, as the filtrate fractions had been before, by absorption and arc spectra, color of the oxide and average atomic weight. The results are shown in Table IB. The evidence from the intensities of the lines in the arc spectra is conclusive upon at least one point, namely, that La, Nd, and Sm are strongly concentrated in the filtrate fractions while the abundant Y, accompanied by Er and Yb, is strongly concentrated in the regenerate fractions. With respect to the way in which these elements are concentrated among the various individual fractions of the filtrate and regenerate portions, the arc spectra give little evidence, but the absorption spectra, the colors of the oxides and the atomic weight determinations e m i t somewhat more definite conclusions. In the filtrate fractions La is the first to appear a t the base of the column; this is followed by Nd TABLEI FRACTIONATION OF AN YTTRIUMGROUPMIXTUREBY MULTIPLE-STAGE OPERATIONS Orig. av. at. wt. 111.8 ( ~ 0 . 1 ) Fraction No. 1-3 4-10 11-14 16 16 17 18
Color of oxide, Absorption At wt A. Filtrate Fractions Very light brown Light brown Medium brown Nd w u k Medium brown N d weak Medium brown N d medium, Pr?, Sm faint Red brown N d medium, Pr?, Sm faint Red brown, 127.6 (*O 1)
1 2 3 4-5 6 7 8-9 10 11-17
B. Regenerate Fractions Nd medium, Pr?, Sm weak Medium brown N d medium, Pr?, Sm weak Medium brown, 105 9 ( * O 0 ) N d medium Medium brown N d weak Light brown ?id faint Light brown Very light brown, 106 2 ( * O 4) Nd faint None Very light brown None Very light brown, 104 1 ( 1 0 1) None Yellowish white, 93 8 ( +O 3)
...
April, 1943
FRACTI~NATION OF THE RARIE EARTHS BY ZEOLITEACTION
599
and apparently by Sm. In the regenerate frac- of the present writers in which solutions of Fe+a tions the first to appear at the base of the column and T h t 4 , with various ratios of the concentrais Nd (accompanied by the small amount of La which is still present) and apparently followed by Sm, Y , E; and Yb in that order. It is evident that two fractional separations are obtainable by the action of a zeolite upon a rare earth solution. These separations occur, in the first place, upon the original contact of the solution with the zeolitic material and, secondly, upon the regeneration of the material by the action of concentrated sodium chloride solution.
tions of the two cations, have been run through short columns of the base-exchange resin Amberlite IR l.17 The effect of varying proportions of the individual rare earths in the original mixture, therefore, is as yet unknown but it is felt that it may be considerable, great enough possibly even to reverse the order of preference, especially in the case of neighboring elements of closely the same size. S. W. Melsted and R. H. Bray have indicated the existence of a further concentration effect in The Mechanism of Zeolite Action base-exchange reactions. They have stated1* When the rare earth solution is run through the “that both the total concentration of the soluzeolite column, the ions for which the lattice tion and the nature of the base-exchange material has most affinity are most strongly held toward the may be so modified as to either increase or detop of the column. The others are forced to pass crease the relative accumulation of a given ion farther down before they, in turn, are admitted on the exchange material and that if the valence to the lattice in exchange for Na+ ions. When of one of the ions could be changed it would fresh material is again added at the top, the ions change its relative accumulation.” Ivanov and most loosely held are driven still farther down Gapon, on the other hand, have concl~ded’~ the column. I n this way, if the capacity of the that dilution of the solution does not affect to a zeolite is reached (by forcing into contact with different extent mixed ions of the same valence. it more ions than it can hold) and if the conditions A further examination of the importance of for equilibrium are approached, then the first such concentration effects as well as more quanions to be ejected from the base of the column are titative studies of other aspects of the zeolitethose for which the &nity of the base-exchange rare earth ion equilibria will be undertaken in medium is least. Under the conditions of the this Laboratory. experiments here reported the ion with least Acknowledgment.-Thanks must be expressed tendency to be held in the lattice is La+3. to The International Filter Company, The Upon regeneration of the zeolite even the most Permutit Company, The Graver Tank Company, strongly-held ions are removed by the action of The Zeolite Sales Company and The Resinous the high concentration of Na+ ion; they pass Products and Chemical Company, all of which down the column ahead of the most concentrated generously made available samples of their layer of regenerating solution but force ahead of various base-exchange materials. them, in the same way, the ions which are even Summary and Conclusions more readily removed. The latter, then, are The phenomenon of base-exchange is more the first to come from the column and the others general than has often been supposed. In this follow in the order of increasing affinity for the preliminary study no cation was encountered the lattice with Y+a,and probably the ions H O * to ~ valence or the size of which was so large that it L U + ~issuing , last. was unable to enter into base-exchange reactions. The Concentration Effects Fractional separations within the rare earth group are obtainable by means of zeolite action From the equilibrium principle it seems reasonwhen concentrated solutions, containing sufficient able to expect that an ion with somewhat lesser ions to exceed the capacity of the exchangeaffinity for the lattice would be held in the zeolite material, are used. The rare earth ions of deeven more strongly than an ion with normally creasing (crystal) ionic radius are held more greater affinity for the lattice if the former were firmly in the zeolite lattice while the larger ions much more abundant in the solution. The exist(17) The Resinous Products and Chemical Co., Philadelphia, Pa. ence of such an effect has been indicated by (18) Personal communication. Bray7 and has been suggested also by some work (19) A. N. Ivanov and E. N. Gapon, C. A., 38, 4005 (1942).
600
HARRYSELTZ, F. J. DUNKERLEY AND B. J. DEWITT
are held less firmly. The removal of rare earth ions by regeneration of the base-exchange material may also be carried out: in a fractional
[CONTRIBUTION FROM THE
Vol. 65
manner with the largest, most loosely-held ions being removed first WEST
DEPARTMENT OF CHEMISTRY OF
LAFAYETTE, INDIANA RE~EIVED OCTOBER 15,1942
THE ChRNEGIE INSTITUTE OF TECHNOLOGY]
Heat Capacities and Entropies of Molybdenum and Tungsten Trioxides BY HARRYSELTZ, F. J. DUNKERLEY AND B. J. DEWITT' The heat capacity measurements reported in this paper were carried out in a calorimeter described in a previous publication.' Several improvements have been made, however, in this apparatus. A new Calorimeter can has been constructed, wound with no. 40 double silk insulated gold wire amtaining 0.175$0 of silver, and the heavy calorimeter shield was rewound with the same wire. These windings have shown consistently constant temperature-resistance readings over a period of a yeas-. To increase the mass of the shield a heavy copper screw top was added, giving a total mass of 4890 g. The vacuum vessel for the calorimeter was rebuilt with a seal in the form of a V, which was partly filled with eutectic composition solder and into which the lid fitted loosely. The solder in this well was melted by a coil of chrome1 wire wound around the outside. With this type of seal no vacuum difficulties, such as were sometimes encountered with a bolted lid, appeared, and pressures between and lowfi i n m . were readily maintained using a two-stage vapor pump backed by a Cenco Hyvac. For pumping off liquid nitrogen a second large capacity container, completely inclosing the calorimeter set-up, was made vacuum tight by a similar type of seal, and a high capacity threestage steam ejector was employed in this pumping-off operation. Temperatures as low as S ° K . have been reached by this means. Materials.-The molybdic oxide used in these measurements was Baker's Analyzed, containing less than 0.1% of impurities. Under the microscope it consisted of very small transparent rhombic crystals. This material was dried in an oven t o constant weight and was kept in a desiccator until ready for use. The total charge in the calorimeter was 139.055 g. zn wucuo, or 1.0316 moles. The tungstic oxide was prepared by the method de(1) Abstracted, in part, from a thesis presented by B. J. DeWitt the committee on Graduate Instruction of the Carnegie Institute of Technology, in partial fulfillment of the requirements fnr the degree of Doctor of Science, June, 1941 i o ) Mcnonnid and Srltz THP J O U R N A L , 61, ,240; 11939) to
scribed by Schumb and Hartford.8 A hot solution of reagent grade sodium tungstate was treated with hydrochloric acid, and the precipitated tungstic acid was washed free from chlorides. This was dissolved in hot ammonium hydroxide, and ammonium tungstate was crystallized from this solution. After three recrystallizations the hot solution of the purified tungstate was treated with nitric acid and the precipitated tungstic acid was digested on a waterbath for several hours. This material, which filtered readily, was washed, dried in an oven and finally ignited to 775' for ten hours. It was kept in a desiccator in the dark until ready for use. Under the microscope it showed very fine rhombohedral crystals. The charge of the oxide used in the heat capacity measurements was 135.446 g. in
TABLEI MOLALHEATCAPACITIES Temp., OK.
70.05 74.48 79.75 83.95 87.70 91.15 97.55 101.79 105.58 109.22 114.00 117.63 121.72 129.30
Molal
CP
4.73 5.09 5.53 5.90 6.27 6.48 7.20 7.58 7.90 8.23 8.61 8.75 9.19 9.70
Temp., OK.
134.07 142.25 144.65 151.50 154.87 159.51 163.47 169.45 179.40 182.50 186.37 192.46 201.05 208.92
OF
lM0O.s
Molal
Temp.,
Molal
10.00 10.40 10.68 11.12 11.32 11.66 11.90 12.30 12.78 13.08 13.16 13.47 13.85 14.21
212.87 220.05 224.12 230.39 234.69 240.15 250.67 254.86 260.30 268.20 280.32 294.72 298.73
14.35 14.66 14.79 15.08 15.25 15.53 15.96 16.15 16.31 16.60 17.01 17.50 17.60
CP
OK.
CP
TABLE 11 MOLALHEATCAPACITIES OF WO, 'Temp., 'K.
.Molal
62.90 63.3i 68.98 71.55 75.25 79.68 84.20 88.90 93.80 105.22 112.44
4.21 4.34 4.87 5.21 5.44 5.94 6.26 6.68 7.18 8.30 8.73
CP
Temp, OK.
120.52 126.86 136.30 144.96 152.88 160.16 167.68 177.86 183.46 189.08 203.95
Molal
CP
9.58 10.18 10.90 11.43 12.06 12.68 13.15 13.75 14.09 14.40 15.26
Temp.. OK
212.20 216.13 230.95 236.40 242.85 251.79 267.50 273.68 287.03 299.20
(3 Schrimh and Hartford, i b i d . . 66, 2613 (19341.
Molal
c9 15.75 15.99 16.70 16.90 17.25 17.50 18.19 18.46 19.10 19.55
